It has long been desired to maximize fuel economy, power and driveability in vehicles while enhancing acceleration, reducing emissions, and preventing hesitation. While it is known to enhance gasoline powered engine performance by employing dispersants to keep valves and fuel injectors clean in port fuel injection engines, such gasoline dispersants are not necessarily effective fuel injected diesel engines and may not be as effective in low sulfur fuels. The reasons for this unpredictability lie in the many differences between the fuel compositions that are suitable for such engines.
Additionally, new engine technologies require more effective additives to keep the engines running smoothly. Additives are required to keep the fuel injectors clean or clean up fouled injectors for spark and compression type engines. Engines are also being designed to run on alternative renewable fuels. Such renewal fuels may include fatty acid esters and other biofuels which are known to cause deposit formation in the fuel supply systems for the engines. Such deposits may reduce or completely bock fuel flow, leading to undesirable engine performance.
Some additives, such as quaternary ammonium salts that have cations and anions bonded through ionic bonding, have been used in fuels but may have reduced solubility in the fuels and may form deposits in the fuels under certain conditions of fuel storage or engine operation. Conventional quaternary ammonium salts may not be effective for use in diesel fuels containing components derived from renewable sources. Certain quaternary ammonium salts may not be effective for use in petroleum-based diesel fuels. Accordingly, there continues to be a need for fuel additives that are effective in cleaning up fuel injector or supply systems and maintaining the fuel injectors operating at their peak efficiency.
Also, low sulfur fuels and ultra low sulfur fuels are now common in the marketplace for internal combustion engines. A “low sulfur” fuel means a fuel having a sulfur content of 50 ppm by weight or less based on a total weight of the fuel. An “ultra low sulfur” fuel means a fuel having a sulfur content of 15 ppm by weight or less based on a total weight of the fuel. Low sulfur fuels tend to form more deposits in engines than conventional fuels, for example, because of the need for additional friction modifiers and/or corrosion inhibitors in the low sulfur fuels.
In accordance with the disclosure, exemplary embodiments provide a fuel additive concentrate for use in injected fuel engines, a method for cleaning fuel injectors for an internal combustion engine, a method for restoring power to a diesel fuel injected engine, a fuel composition, a method for improving performance of fuel injectors, and a method of operating a fuel injected diesel engine. The additive concentrate includes (a) a hydrocarbyl substituted quaternary ammonium internal salt; and (b) a reaction product derived from (i) a hydrocarbyl substituted dicarboxylic acid, anhydride, or ester and (ii) an amine compound or salt thereof of the formula
wherein R is selected from the group consisting of hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from the group consisting of hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product (b) on average has less than 2 amino-triazole groups per molecule. One weight ratio of (a) to (b) in the additive concentrate ranges from about 10:1 to about 1:10.
Another embodiment of the disclosure provides a method of improving the injector performance of a fuel injected diesel engine. The method includes operating the engine on a fuel composition that includes a major amount of fuel and from about 5 to about 500 ppm by weight based on a total weight of the fuel of a synergistic fuel additive. The synergistic fuel additive includes (a) a hydrocarbyl substituted quaternary ammonium internal salt; and (b) a reaction product derived from (i) a hydrocarbyl substituted dicarboxylic acid, anhydride, or ester and (ii) an amine compound or salt thereof of the formula
wherein R is selected from the group consisting of hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from the group consisting of hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product (b) on average has less than 2 amino-triazole groups per molecule. A weight ratio of (a) to (b) in the fuel additive ranges from about 10:1 to about 1:10. With the synergistic additive(s) present in the fuel, in one embodiment, at least about 90% of the power lost during a dirty up phase (when no inventive additive(s) is present in the fuel) of a CEC F98-08 DW10 test is recovered.
A further embodiment of the disclosure provides a method of operating a fuel injected engine. The method includes combusting in the engine a fuel composition containing a major amount of fuel and from about 5 to about 500 ppm by weight based on a total weight of the fuel of a synergistic fuel additive. The synergistic fuel additive includes (a) a hydrocarbyl substituted quaternary ammonium internal salt; and (b) a reaction product derived from (i) a hydrocarbyl substituted dicarboxylic acid, anhydride, or ester and (ii) an amine compound or salt thereof of the formula
wherein R is selected from the group consisting of hydrogen and a hydrocarbyl group containing from about 1 to about 15 carbon atoms, and R1 is selected from the group consisting of hydrogen and a hydrocarbyl group containing from about 1 to about 20 carbon atoms. The reaction product (b) on average has less than 2 amino-triazole groups per molecule. A weight ratio of (a) to (b) in the fuel additive ranges from about 10:1 to about 1:10.
An advantage of the fuel additive described herein is that the additive may not only reduce the amount of deposits forming on fuel injectors, but the additive may also be effective to clean up dirty fuel injectors sufficient to provide improved power recovery to the engine. The combination of components (a) and (b) in a fuel may be synergistically more effective for improving injector performance and power recovery (power restoration) than each of the components (a) and (b) alone in the fuel.
Additional embodiments and advantages of the disclosure will be set forth in part in the detailed description which follows, and/or can be learned by practice of the disclosure. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.